OBJECTIVE To discuss the protective effect of Mailuoning injection on ischemia/reperfusion (I/R) injury in rats and its mechanism. METHODS Healthy male adult Sprague-Dawley (SD) rats were randomly divided into the sham operation group, the model group, the edaravone (3 mg x kg(-1)) control group, and Mailuoning high, middle and low-dose groups (4, 2, 1 mL x kg(-1)), with 10 rats in each group, and administered with drugs through tail intravenous injection. The middle cerebral artery occlusion (MCAO) was adopted to establish the rat ischemia/reperfusion model. After the ischemia for 2 h and reperfusion for 24 h, the pathological changes in neurovascular units (NVU) of brain tissues at the ischemia side was observed by HE staining. The expressions of glialfibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule 1 (Ibal) were detected by the immunohistochemical method. The expressions of tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were detected by the western blotting technique. RESULTS Mailuoning injection could significantly improve the pathological changes in cortical penumbra brain tissue UVN of (I/R) rats, reduce the number of GFAP and Ibal positive cells, and significantly decrease the expressions of TNF-alpha, IL-1beta, VCAM-1 and ICAM-1 of brain tissues of I/R rats. CONCLUSIONS Mailuoning injection shows an obvious protective effect on UVN of I/R rats. Its mechanism may involve the inhibition of the activation of astrocyte and microglia and the secretion and expression of various inflammatory factors.